The present invention relates to collating apparatus for forming a stack or row of similar articles, especially articles having a generally flat configuration.
Continuous processes producing a series of individual articles at a high rate usually require means for collating the articles at the end of the production line in an orderly manner prior to packaging them for distribution. EP-A-0059840 and DE-A-3708604 for example, disclose collators which collect flat packets of uniform size in stacks having a specified number of packets.
Thus, in DE-A-3708604 a collator has a chute provided with cantilevered platforms which travel downwards past the end of the horizontal conveyor belt from which the articles tip onto the platforms. The rate of delivery of the products is synchronised with the speed of descent of the platforms. A horizontal pusher below the conveyor belt has its movement coordinated with the movement of the platforms to clear the stack which has been completed on each platform as its descends to the level of the pusher. Such an arrangement is limited in its rate of operation, especially in handling flat products, e.g. because the rate of delivery of the product must not exceed the capacity of the pusher to move the stacks stably without obstructing the regular delivery of further articles to the collator.
In DE-A-3736868 the stack of articles is built on a chute, similarly provided with cantilevered support platforms. In one arrangement the stack is built on such platforms which are mounted on circulatory bands that progressively lower the platforms to maintain the top of the building stack at a constant height, and a corresponding second set of platforms on circulating bands is disposed below the first. As it is completed the stack of articles is dropped from the first set of platforms to the second set and the second set then lower the stack to a position in which an extractor device can be inserted into the chute to expel the stack. The second set of platforms acts as a buffer to hold the completed stack while the next stack begins to build.
This arrangement is also limited in its speed of operation and has a number of other significant disadvantages. The transfer of the completed stack and the return of the first set of platforms to a stack-building position takes a certain amount of time and this must not exceed the rate of delivery of the articles. Furthermore, this time period will increase with the height of the stack. The stack must then fall under gravity onto the second set of supports without disruption and this can pose an even more severe limitation on the height of the stack.
In all these chute-like arrangements for forming a stack there is also the problem that the articles will often be easily deformable and if packed as a free-standing stack they will move in the container, becoming disordered and even being damaged. It is therefore desirable to pack the stacks in a slightly compressed state, but an additional operation is needed for this, after the stack has left the collating apparatus.